The present invention relates to an optical transmission module in which electronic parts are connected through a flexible substrate.
The conventional optical module which uses a coplanar waveguide is known in Japanese Patent Laid-Open No. 9-148675 and Japanese Patent Laid-Open No. 2002-335034. The patent document 1 describes a mounting structure of an optical module in which a connection is made at least between a terminal block of a package and a substrate for a luminous element by use of a flexible substrate on which a stripe-shaped signal conductor and ground conductors parallel with, and on both sides of, the signal conductor are place so as to form an insulated layer, and for which impedance matching is performed. In addition, the patent document 2 describes an optical module in which an electrical connection is made between a semiconductor laser and an electric signal input/output section of a package by use of a feedline comprising a dielectric substrate made of a material, the thermal conductivity of which is lower than that of aluminum oxide, and a conductor film formed on the dielectric substrate.